The present invention relates to heat exchangers and especially to a solar heating panel using an improved heat exchanger.
In the past, a wide variety of solar heaters and solar panels have been provided for heating hot water and also for heating buildings. A typical solar heater provides a base panel having short sides and a serpentine passageway of pipes passing therethrough. The panel may be covered with glass to prevent the escape of the heated inside of the panel and may have the base coated black for capturing the heat energy from the sun rays within the glass enclosed panel. Pipes passing through the panel are typically made of copper to absorb the heat in the panel, but a variety of other materials and techniques have also been suggested. The tubing used in solar heaters usually has a smooth straight flow path so that the liquid passes through the tubing too fast to obtain the maximum benefit from the solar heat. The solar heating panel is connected to an electric water heater where the solar heated water can be mixed with electrically heated water as needed to obtain sufficient hot water.
The present invention relates to a solar panel of this type having an improved heat exchanger replacing the serpentine passageway of pipes through the panel for an improved efficiency in collecting the heat in the panel. Other prior art solar heaters use parabolic dishes, lenses and mirrors to direct the sun rays against tubes which are typically painted black, and it should be clear that the heat exchanger of the present invention is also ideally suited for this type of solar heater. The present heat exchanger has a helical tube folded with a metallurgical seal to bond it to the outside of a hollow copper tube.